Dust clog indicator



Jan. 3, 1950 w. R. ROSE DUST CLOG INDICATOR Filed Aug. 1, 1946 Fatented Jan. 3, 195v ZAQEJM UNIT-ED 0 FEF I CE DUST CLOG INDICATOR William R. Rose, Arlington," Va.

Application August 1, 1946, Serial No. 687,788

.5 Claims. 1

This inventionrelates to animproved dust .clog

indicator forthe. air filter screens. of hot. air furnaces.

In=so far-asI am aware, novisibleindlcator or other means is at the present time i'n.use..in

-' con-junction with .the .filtemscreens of conventional circulatory hot air furnace systems .to apprise the user of the'furnace 0t such-asystem. that ithevair filterscreens of theiurnacei are, in any vdegree, clogged withdust. :Rather, the user is told to install. new screens every.so 0ften,.or even .periodicall'y. The installation of new. screens is thus overlooked. or neglected especially 7 by .per- ..sons not mechanically inclined vvsufficiently to tamper with the furnace, with the. result thatthe :filter screens become more and. more. clogged,- with dust until a conditionisreached wherein the air fan isunableto circulate little, if. any, airthrough v the screens and through 1 the system, so that the dwelling or building, as the case may:be,:bec0mes ,more or less chilly or cold at all times even though the burneriof. the furnace is obviously function- .ing satisfactorily.

The present invention,,-therefore,l seeksv to prov-ide a devicewhich-willeliminate the necessity ofperiodic inspectionbytheusenot the air filter screens themselves, and which willvisibly indi- .catewhether or not the screens are clogged with .dust.

VA further object is tolprovidealdevice which will visibly indicate,- more or less .roughly, just .abouthowibadly the..filter screens are clogged.

And the invention: seeks as. a stillifurther object, to provide. a device which-will-be.simple and cheap, andwhichmayhe readily. applied. tor tur- .naces already in 1158x215 well. as new ifurnace =installati'ons.

Other, and incidental obi ects. of I the invention will appearlduring the course. of theifollow ing de- ..scription, and-iini the drawings:

:Figure 1 isia. side elevation-.,showing my im- 1proved device applied-to a conventional hot air furnace.

Figure 2 is adetail front elevation ofthe device.-

lreturn inlet duct I I, and ahot air outletrd'uct H; Removably mountedat' the upper portiomof the chamber ID are one or more approved air filter screens l3. and mounted within the lower .zontal, as shown-,onslightly inclined wupwardly, if

portion-cf said chamber is a suitable air fan building serviced by the furnace is drawnby the fan M throughthe. duct H and through the screens 13 into thel chamber. l0, and thence discharged by the fan .from said chamber through the duct I 2. .Ithas [been deemed. unnecessary. to show any means for heating the air.

All of the vforegoingstructure as well as the operation thereof is -.-well-. knownin many variations in the art,v audit is therefore unnecessary to go intoa showingloridescription of. detailother than the general disclosureoutlined- However, it should be noted thatone of the prevailing .difficulties experienced. in connection with all. such installations arises through. the; fact that the screens I 3 become, incident to conti'nueduseof the furnace, as, for instance, duringa winter, more and more clogged with dust until acondition is reached such that thefan it cannot. draw Under such a condition, the famcon- In carrying the present invention into effect,

-I.- employ an Oblong. base block 16 which is pref- :erably formed'ofa-glass- However, if found expedient, the baseblock maybe-formed ofmetal, orv synthetic material either transparent ornontransparent. The base' block-is -fiatwat its rear side, and projecting'from the upper end'portion thereof medially of theblock his a nipple V l 1. At .its forward side, theblock is provided with side walls 18 and -l,9.respectively, as well as with end walls 26, and formed on thebottom wall-of the block at oppositesides'ofthe nipple H are spacing bosses 2|.

As will be seen, the side walls l-B and I9 in conjunctionwith the end walls-2E provide a chamberZZ, and formedin the side wall I8 is an air inlet opening zscommunicating withalongitudinal passage v. 4 insaid wall. The passage 24 opens into the chamber 22 near the lowerend thereof, and extending later-ally from'the mouth of said passage is--a moreorlesssshorti horizontal baffle .25, thelower --.1-ace .of which. may lbeihoriso desired.

Extendinga horizontally fromtheside wall 18 'of the block It ahovetherbafile Z5118 'a longer baflle 2%, above whichsis a like bafiiei2'lrextendingfrom the sideu alllfil of the 'blfock, and-arranged above ing fromithe side'avall 2H3;v *All' 'of-fthe bafiiesyare preferably integral with the base block and of the same material.

overlying the side and end walls of the base block I6 is a cover plate 29 abutting the bosses 2i. Regardless of whether or not the base block is transparent or non-transparent, the cover plate is, in any event, of transparent material and may be formed of glass or approved synthetic substance. Preferably, the cover plate is secured in place by a suitable cement, or otherwise mounted in position to seal the cover plate air-tight, and likewise close the chamber 22 at its forward side. conceivably, the cover plate could be fused in position.

In devising the device, effort has been made to render the attachment thereof to the furnace as simple as possible. As shown in Figure 4, it is only necessary to provide a wall 30 of the fan chamber In with an opening to receive the nipple H, a gasket 3| around the nipple being preferably employed, and extending through the cover plate 29 and through the bosses 2| are cap screws 32 engaged through said wall for detachably securing the device in operative position. Thus, communication is established, by means of the nipple I1, between the fan chamber In of the furnace and the chamber 22 of the base block [6.

In use, the lower portion of the chamber 22 of the device is partially filled by a pool of suitable liquid, indicated at 33. Water may be employed, although a more viscous liquid, or other liquid less subject than water to evaporation may well be used. In any event, the pool of liquid 33 is at a level, normally, say half-way between the baiiies 25 and 26, and may be replenished by introducing additional liquid through the opening 23.

Assuming now that the fan M of the furnace is in operation and that the screens i3 are new to permit unimpeded flow of air therethrough, the indicator, as above described, will be unaifected. However, as the screens l3 become clogged with dust, the suction effort of the fan M will be communicated through the nipple I! to the chamber 22 of the base block it. Consequently, as the screens 13 become more and more clogged with dust and the suction effort of the fan becomes more and more pronounced, air will be drawn in through the opening 23 and through the passage 24 to emerge along the under surface of the baffle 25 in a series of bubbles, indicating that the screens are in proportionate degree clogged. At the inception of the clogging of the screens such as to reflect in a proportionate suction effort of the fan 14, the bubbles of the stream of bubbles along the under surface of the baffle 25 are spaced more or less wide apart and the motion thereof is slow and hesitating. However, as the screens become still more clogged, the motion of the stream of bubbles is quickened proportionately, and the bubbles become more and more closely spaced relative to each other until, when the screens are practically impervious to the passage of air therethrough, the stream of bubbles is very rapid in motion and uninterrupted, while the bubbles of the stream are close together. Thus, by observing through the cover plate 29, the presence or absence of a stream of bubbles rising through the pool of liquid 33, as well as the spacing of the bubbles of the stream and the rapidity of motion thereof, the user may determine whether or not the screens 13 are clogged with dust, and, if any, just about how badly clogged. The baflies 26, 21, and 28 are provided as a safeguard to prevent liquid from the pool 33 from being sucked upwardly through the nipple ll into the fan chamber of the furnace.

Having thus described my invention, I cl m:

1. A clog indicator for the air filter scree of a furnace having a stream of air drawn by a an through said screen, said indicator includng means providing an air intake, and means adapted to interpose a pool of liquid between said air intake and said air stream submerging a portion of said air intake whereby to provide bubbles of air rising through said pool of liquid as said screen becomes clogged and the suction effort of the fan is thereby increased.

2. A clog indicator for a furnace air filter screen including a base block providing a chamber and having an air inlet passage entering said chamber, a cover plate closing said chamber to receive a pool of liquid submerging the mouth of said passage, and means for operatively connecting said chamber with a furnace whereby air will be drawn in through said inlet passage to rise through said liquid and form bubbles as said screen becomes clogged.

3. A clog indicator for a furnace air filter screen including a base block providing a chamber and having an air inlet passage entering said chamber, a cover plate closing said chamber to receive a pool of liquid submerging the mouth of said passage, and means for operatively connecting said chamber with a furnace whereby air will be drawn in through said inlet passage to rise through said liquid and form bubbles as said screen becomes clogged, a portion of said cover plate being transparent to afford a view of said bubbles.

4. A clog indicator for a furnace air filter screen including a base block providing a chamber and having an air inlet passage entering said chamber, a cover plate closing said chamber to receive a pool of liquid submerging the mouth of said passage, and a nipple carried by the base block to communicate with said chamber and adapted to operatively connect said chamber with a furnace whereby air will be drawn in through said inlet passage to rise through said liquid and form bubbles as said screen becomes clogged.

5. A clog indicator for a furnace air filter screen including a base block having side and end walls providing a chamber, one of said walls being formed with an air inlet passage entering said chamber and the block being provided with a bafile near the mouth of said passage, a cover plate abutting said side and end walls and closing said chamber to receive a pool of liquid submerging the mouth of said passage, and a nipple carried by the base block to communicate with said chamber and adapted to operatively connect said chamber with a furnace whereby air will be drawn in through said inlet passage to travel along the under surface of said baflie and rise through said liquid to form bubbles as said screen becomes clogged, a portion of said cover plate being transparent to afford a view of said bubbles.

WILLIAM R. ROSE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,959,759 Hultberg May 22, 1934 2,013,136 Cornelius i Sept. 3, 1935 

